The invention is directed to a method for setting welding parameters for the production of thermal welds between at least two light waveguides.
In practice, the correct setting of what are referred to as welding or, respectively, splicing parameters (such as, for example, strength of welding current, welding duration, welding energy, electrode spacing, electrode position, etc.) can be made more difficult for thermal welding, particularly fusion welding, of light waveguides.
For setting the heat quantity for welding two respective optical fibers in the known method of EP 0 320 978, for example, a bare optical fiber end is exposed to heat, is thereby melted and rounded off due to the surface tension of the glass material which has been rendered viscous. As a result thereof, the fiber end retracts from its original final position before the welding process. That distance by which the fiber end melts back in the longitudinal fiber direction under the influence of heat and thereby shortens in length corresponds to the activated heat quantity. It is measured in order to quantitatively acquire and then set this heat quantity. This known procedure, however, is highly affected by errors. One reason for this is, in particular, that the welding conditions during the rounding procedure deviate too greatly from those during normal welding of two optical fibers.
The invention is based on the object of disclosing an improved way how one or more welding parameters for thermal welding of light waveguides can be set under a multitude of practical conditions. This object is inventively achieved in a method of the species initially cited in that at least one test optical fiber section is subjected to a defined tensile stress during a prescribable testing time; in that the test optical fiber section is heated in at least one longitudinal location during this stress load; and in that a constriction that forms at the heating location at the outside circumference of the test optical fiber section under the continuing tensile stress is acquired and utilized for setting one or more of the welding parameters.
This makes it possible to adapt the welding or, respectively, splicing parameters to different welding or, respectively, splicing conditions (such as, for example, atmospheric moisture, air pressure, air temperature, optical fiber type, electrode condition, etc.) in a simple as well as reliable way. An improved splice quality can be achieved in this way.
The invention is also directed to a method for welding respectively two optical fibers allocated to one another, whereby at least one preliminary trial in at least one test optical fiber section is first implemented for the respectively currently existing welding conditions in order to determine an optimum set of welding parameters, whereby the test optical fiber section is subjected to a defined tensile stress in this preliminary trial for a prescribable testing time, whereby the test optical fiber section is heated in at least one longitudinal location during this tensile stress so that a constricting effect is produced thereat at the heating location at the outside circumference of the test optical fiber section under the continuing tensile stress, whereby this constricting effect is acquired and utilized for optimizing the set of welding parameters for the existing welding conditions, and whereby the weld of two respective optical fibers to be actually welded to one another is produced only after this at least one preliminary trial, being produced with the identified, optimized set of welding parameters.
The invention is also directed to an apparatus for setting welding parameters for producing thermal welds between at least two optical waveguides which is characterized in that at least one traction means is provided with which at least one test optical fiber section can be subjected to a defined tensile stress during a prescribable testing time; in that at least one heating device is provided with which the test optical fiber section residing under tensile stress can be heated in at least one longitudinal location; and in that means are provided with which a constriction being formed at the outside circumference of the test optical fiber section can be acquired and utilized for setting one or more of the welding parameters.